In an icy lake half a mile beneath the Antarctic ice sheet, scientists have discovered a diverse ecosystem of single-celled organisms that have managed to survive without ever seeing the light of the sun.
The discovery, reported in the journal Nature, is not so much a surprise as a triumph of science and engineering. The research team spent 10 years and more than $10 million to prove beyond a shadow of a doubt that life did indeed exist in subglacial lakes near the South Pole.
“It’s the real deal,” said Peter Doran, an Earth scientist at the University of Illinois at Chicago, who was not involved in the study. “There was news that they found life early this year, but a bunch of us were waiting for the peer-reviewed paper to come out before we jumped for joy.”
John Priscu, the lead scientist on the project, has been studying the Antarctic for 30 years. He published his first paper describing how life might exist in the extreme environment beneath the ice sheet in 1999, and has been looking for definitive proof ever since.
In the winter of 2013-14, he finally got his chance. After spending millions on a drill that could bore a clean hole free of contaminants through the ice sheet, and moving more than 1 million pounds of gear on giant sleds across the Antarctic ice sheet, he and his team had just four frenzied days to collect the water samples that would prove whether his theories were right or wrong.
Before claiming victory, he wanted to see three lines of evidence that life did exist in the underwater lake. He wanted to see the cells under a microscope, he wanted to prove they were alive by feeding them organic matter and measuring their respiration rate, and he wanted to see how much ATT was in their cells.
“I wasn’t surprised to find life under there, but I was surprised how much life there was, and how they made a living,” said Priscu, who teaches at Montana State University. “They are essentially eating the Earth.”
Priscu and his team report the discovery of close to 4,000 species of microbes growing in the cold, dark environment of Subglacial Lake Whillans in western Antarctica. Each quarter teaspoon of the tea-colored lake water that they brought to the surface had about 130,000 cells in it, they write.
“I think we were all surprised by that number,” said Brent Christener of Louisiana State University and the lead author of the Nature paper. “We’ve got lakes here on campus that we can take samples of and the numbers are about in that range.”
Life in the lakes of Louisiana has sunlight to provide it with energy, but in the lightless environment of Subglacial Lake Whillans, the microbes rely on minerals from the bedrock and sediments instead. The pressure of the slowly moving ice above the lake grinds the underlying rock into a powder, liberating the minerals in the rock into the water, and making them accessible to the microorganisms living there, explains Christener. The microbes act on those iron, ammonium and sulphide compounds to create energy.
“Ice, water and rock is all that is really needed to fuel the system,” he said.